Particulate carriers for sorptive impregnants are known. Exemplary are conventional relatively thermostable, sorptive impregnants such as copper and silver salts, on activated carbon particles. Also known are liquid sorptive impregnants such as liquid amines, on particulate carriers. Illustrative are U.S. Pat. Nos. 5,145,820 and 5,462,908 to Liang et al, which describe the deposition of liquid sorptive amines on activated carbon particles by reduced pressure sublimation.
Fibrous structures containing adsorptive particles are commercially available. Filter media or filters made from these structures include sorptive particles for selectively removing certain components of a liquid or gas passing through the filter. Acceptable performance with low pressure drop beneficially results from the sorptive particles being distributed in a three dimensionally spaced apart arrangement and being immobilized in this arrangement. However, the immobilizing step can be detrimental to sorptive particles. For example, physical immobilization techniques such as needling and water jet entangling, can adversely affect sorptive particles.
On the other hand, if heat-bonding is used for immobilizing the sorptive particles, the elevated temperature applied for the bonding could be harmful. Furthermore, chemically aggressive particles could adversely affect the fibrous structure during an elevated heat-bonding step. In addition, moisture in active particles can interfere with heat-bonding. Moreover, there is difficulty in regenerating the functional activity of a fibrous structure having active particles bonded to the fibrous structure.
Accordingly, despite prior advances in this art, an improved fibrous structure having a three dimensional arrangement of immobilized active material, is needed. Such a fibrous structure could beneficially include active material adversely affected by an immobilization step. Furthermore, such a fibrous structure could advantageously include chemically aggressive, active material. In addition, such a fibrous structure would facilitate the recovery and safe disposal of spent active material, and the regeneration of the functional activity of the fibrous structure.